Run results for: document.querySelector vs document.body.querySelector vs getElementsByClassName

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.71 Safari/537.36

Browser: Chrome 94

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
querySelector	3243643.5 Ops/sec
querySelector.body	3238971.5 Ops/sec
getElementsByClassName	4055628.5 Ops/sec
getElementsByClassName BODY	3710478.8 Ops/sec

HTML Preparation code:

<div class="testElement"></div>

Tests:

querySelector
var el = document.querySelector('.testElement');
querySelector.body
var el = document.body.querySelector('.testElement');
getElementsByClassName
var el = document.getElementsByClassName('testElement');
getElementsByClassName BODY
var el = document.body.getElementsByClassName('testElement');